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Abstract (E)-3-Aryl-2-cyanoprop-2-entioamides, prepared by Knoevenagel condensation between aromatic aldehydes and cyanothioacetamide, react with sodium nitrite in acetic acid to form (2E,2′E)-2,2′-(1,2,4-thiadiazole-3,5-diyl)bis[3-arylacrylonitriles]. A possible mechanism and limitations of the reaction are discussed. Molecular docking was carried out in order to search for possible protein targets for the obtained 1,2,4-thiadiazoles. One of the compounds showed a pronounced antidote effect against the herbicide 2,4-D in a laboratory experiment on sunflower seedlings and under field conditions.

The spectral characteristics of dithiomalondianilide (N,N′-diphenyldithiomalonodiamide) were studied, and the dissociation constant was determined by potentiometric titration. Quantum-chemical methods at the B3LYP-D3BJ/6-311+G (2d,p) level were used to calculate the molecular geometry and vibrational spectra of the most stable tautomeric forms of dithiomalondianilide. The bioavailability parameters were calculated, and possible protein targets were predicted by the protein ligand docking method.

BackgroundThe release of Hsp70 chaperone from tumor cells is found to trigger the full-scale anti-cancer immune response. Such release and the proper immune reaction can be induced by the delivery of recombinant Hsp70 to a tumor and we sought to explore how the endogenous Hsp70 can be transported to extracellular space leading to the burst of anti-cancer activity. MethodsHsp70 transport mechanisms were studied by analyzing its intracellular tracks with Rab proteins as well as by using specific inhibitors of membrane domains. To study Hsp70 forms released from cells we employed the assay consisting of two affinity chromatography methods. Hsp70 content in culture medium and extracellular vesicles (EV) was measured with the aid of ELISA. The properties and composition of EVs were assessed using nanoparticle tracking analysis and immunoblotting. The activity of immune cells was studied using an assay of cytotoxic lymphocytes, and for in vivo studies we employed methods of affinity separation of lymphocyte fractions.Results Analyzing B16 melanoma cells treated with recombinant Hsp70 we found that the chaperone triggered extracellular transport of its endogenous analog in soluble and enclosed in EVs forms; both species efficiently penetrated adjacent cells and this secondary transport was corroborated with the strong increase of Natural Killer (NK) cell toxicity towards melanoma. When B16 and CT-26 colon cancer cells before their injection in animals were treated with Hsp70-enriched EVs, a powerful anti-cancer effect was observed as shown by a two-fold reduction in tumor growth rate and elevation of life span. We found that the immunomodulatory effect was due to the enhancement of the CD8-positive response and anti-tumor cytokine accumulation; supporting this there was no delay in CT-26 tumor growth when Hsp70-enriched EVs were grafted in nude mice. Importantly, pre-treatment of B16 cells with Hsp70-bearing EVs resulted in a decline of arginase-1-positive macrophages, showing no generation of tumor-associated macrophages. Conclusion In conclusion, Hsp70-containing EVs generated by specifically treated cancer cells give a full-scale and effective pattern of anti-tumor immune responses.

A series of new hybrid molecules containing 2-furyl and partially saturated pyridine fragments was obtained based on the reaction of cyanothioacetamide with furfural and 1,3-dicarbonyl compounds. The resulting compounds were tested in vivo for analgesic activity (rats) in the orofacial trigeminal pain test. Some the tested compounds showed an antinociceptive effect, superior to that of the reference drug (metamizole sodium).

Abstract The reaction of 2-thioxoazines with chlorokojic acid in the presence of KOH in DMF led to the formation of new hybrid molecules containing fragments of kojic acid and azaheterocycle linked by the SCH2 spacer. In silico prediction of bioavailability parameters was carried out, possible protein targets were predicted by the protein ligand docking method.

Condensation of benzaldehyde with malononitrile and malononitrile dimer (2-aminopropene-1,1,3-tricarbonitrile) in the presence of an excess of morpholine in ethanol afforded the morpholinium salt of 6-amino-2-(dicyanomethylene)-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile. The latter, under the Mannich reaction conditions with the participation of primary amines and formaldehyde, gives 6-amino-2-(dicyanomethylene)-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile, 2-(dicyanomethylene)-6-(hydroxymethylamino)-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile or zwitterionic aminomethylation products, 6-(ammoniomethylamino)-3,5-dicyano-4-phenylpyridin-2-yl)dicyanomethanides. Structure of the obtained compounds was established using 2D NMR spectroscopy and single crystal X-ray diffraction analysis. In silico predictive analysis of the biological activity of new compounds was carried out.

The reaction of 2,6-dichloro-4-methylnicotinonitrile with malononitrile dimer in the presence of triethylamine leads to regioselective nucleophilic substitution of the chlorine atom at position 6 with the formation of triethylammonium 2-amino-3-(6-chloro-5-cyano-4-methyl-pyridin-2-yl)-1,1,3-tricyanoprop-2-en-1-ide. The structure of the product was confirmed by spectral methods and X-ray diffraction analysis.

The reaction of partially saturated derivatives of 3-aminothieno[2,3-b]pyridine-2-carboxamide with phthalic anhydride in acetic acid or DMF on heating leads to the formation of thieno[2′,3′:5.6]pyrimido[2,1-a]isoindole derivatives fused with a pyridine or quinoline core. One of the obtained compounds shows a pronounced UV fluorescence.

A number of europium(III), terbium(III), and gadolinium(III) coordination compounds with N-substituted phthalamic acids were synthesized. Composition and structure of the ligands and the obtained complex compounds were confirmed by NMR and IR spectroscopy and thermogravimetric analysis. It was found that terbium(III) and europium(III) coordination compounds with N-phenylphthalamic acid possess the most pronounced luminescence.

Abstract The reaction of 2-amino-1,1,3-tricyanopropene (malononitrile dimer) with isothiocyanates leads to 1-substituted 4,6-diamino-2-thioxo-1,2-dihydropyridine-3,5-dicarbonitriles or 4,6-diamino-2-(phenylimino)-2H-thiopyran-3,5-dicarbonitrile, depending on the conditions. Quantum-chemical modeling of the IR spectra and reaction routes for the synthesized compounds was carried out. In silico predictive analysis of potential protein targets, compliance with bioavailability criteria, and ADMET parameters was performed.

For the first time, cross sections of the 151Eu(α,xn)155−xTb (x = 2–6) reactions were measured by stack foil technique in the alpha particle range 60 → 19 MeV. Experimental excitation functions were compared with theoretical data from TENDL 2019 library and calculated by EMPIRE-3.2.3 code. Thick target yields for terbium radioisotopes were calculated. The possibility of the practical application of the studied reactions for the production of 152Tb and 149Tb was assessed. It was shown that higher energy of alpha particles is required to produce 149Tb. The production of 152Tb is affected by the influence of side reactions. It is possible to decrease the total content of impurities (153Tb+151Tb) at EOB to 18% of the activity of the 152Tb under 8-hour irradiation by limiting the energy range of incident particles to 42 → 34 MeV. The 152Tb yield will be 222 MBq/μA.

Sequential reaction of cyclohexanone with malononitrile and 2-aminopropene-1,1,3-tricarbonitrile in the presence of potassium hydroxide or sodium ethylate in ethanol gave 4-imino-2-(dicyanomethylene)-3-azaspiro[5.5]undecane-1,5-dicarbonitrile. The latter reacted with primary amines and an excess of formaldehyde to form new 2-(dicyanomethylene)-3,7-diazaspiro[bicyclo[3.3.1]non-3-ene-9,1′-cyclohexane]-1.5-dicarbonitrile derivatives. Contrary to the literature data, the reaction of cyclohexanone with 2-aminopropene-1,1,3-tricarbonitrile in benzene in the presence of piperidine and glacial acetic acid led to the formation of 2,4-diamino-5,6,7,8-tetrahydronaphthalene-1,3-dicarbonitrile.

The reaction of aromatic aldehydes with malononitrile, ethyl or butyl cyanoacetate and acetylacetone in the presence of NaOH under mild conditions (EtOH, 25°C) led to the formation of new series of (1S,5R,6R,9R)/(1R,5S,6S,9S)-2-amino-6,9-diaryl-7-acetyl-8-methyl-4-oxo-5-cyano-3-azabicyclo[3.3.1]nona-2,7-diene-1-carboxylic acids esters. A plausible mechanism of the cascade reaction was proposed.

New Eu3+ and Tb3+ complex compounds [Ln(H2O)2L2]Cl∙H2O were synthesized on the basis of coumarin-3-carboxylic acid and its derivatives. Composition and structure of the ligands and the complex compounds were confirmed by NMR and IR spectroscopy, thermogravimetry, and complexometric titration. Europium(III) coordination compounds with coumarin-3-carboxylic and 6-nitrocoumarin-3-carboxylic acids show effective luminescence.

The reaction of (2E,4E)-5-phenyl-2-cyano-2,4-pentadienethioamide or (E)-3-(2-nitrophenyl)acrolein and cyanothioacetamide with α-bromoketones afforded new (2E,4E)-5-aryl-2-(4-arylthiazol-2-yl)penta-2,4-dienenitriles. Direct bromination of the latter by the action of bromine in DMF proceeded regiospecifically at the C5 position of the thiazole ring without affecting the diene system and leads to the formation of new series of (2E,4E)-5-aryl-2-(5-bromo-4-arylthiazol-2-yl)penta-2,4-dienenitriles.

Bromination of (2E)-3-aryl(hetaryl)-2-[4-aryl(hetaryl)-1,3-thiazol-2-yl]acrylonitriles proceeds regioselectively at the C5 atom of the thiazole ring with the formation of new (2E)-3-aryl(hetaryl)-2-[5-bromo-4-aryl(hetaryl)-1,3-thiazol-2-yl]acrylonitriles. The latter were alternatively obtained by the reaction of aldehydes, cyanothioacetamide, α-bromoketones and bromine in the presence of triethylamine in DMF. Structure of the key compounds was confirmed using 2D NMR spectroscopy and single crystal X-ray diffraction analysis.

The reaction of cyanothioacetamide with aromatic aldehydes and 1,3-dicarbonyl compounds followed by aminomethylation or S-alkylation gave a series of heterocyclic derivatives with a 1,2,3,4-tetrahydropyridine or 1,4,5,6,7,8-hexahydroquinoline fragment. The resulting compounds were tested for analgesic activity in vivo. Some of the prepared compounds showed an antinociceptive effect superior to that of ketorolac in dynamics.

1,6-Diamino-2-oxo-1,2,3,4-tetrahydropyridine-3,5-dicarbonitriles under the action of primary aliphatic amines and an excess of 37% formalin in ethanol were converted into 2,3,8,9-tetrahydro-6,10-methano[1,2,4]triazolo[1,5-a][1,5]diazocine-6,10(7H)-dicarbonitrile derivatives. At the same time, the Mannich reaction in the case of 1,6-diamino-4-aryl-2-oxo-1,2-dihydropyridine-3,5-dicarbonitriles proceeds ambiguously, and, depending on the conditions, gives either N-ethoxymethylation products or 1,2,4-triazolo[1,5-a]pyridine derivatives. In silico predictive analysis of the biological activity of new compounds was carried out.

KH-domain PolyC-binding proteins perform many functions ranging from transcription regulation to alternative splicing. There are several evidences of their important role in embryogenesis and in embryonic stem cells (ESCs). ESCs are cultured counterparts of epiblast cells before implantation, and both cell types are in naive state of pluripotency. We have previously shown that members of the KH-domain family—hnRNP-K, Pcbp1 and Pcbp2 proteins—are able to bind to the PolyC-sites within regulatory elements of the Pou5f1 gene that encodes the key pluripotency gatekeeper Oct4. In addition, early lethal phenotype of Pcbp1–/– mouse embryos has been described in literature. In this study, we set to assess role of Pcbp1 in ESCs. To this end, we have obtained null-Pcbp1 ESCs. Contrary to previously observed by us lethal phenotype of hnRNP-K in ESCs, Pcbp1–/– ESCs were viable, continued to express Oct4 and retained overall pluripotent properties. Therefore, the obtained data reveal no critical role of Pcbp1 in self-renewal of naive pluripotent stem cells. Further studies should address whether this is the case during the transition of these cells to the primed state of pluripotency, as well as during the exit from this state due course of differentiation into the three germ layers.

Background/aims Sodium is a key player in the fundamental cell functions. Fluorescent probes are indispensable tools for monitoring intracellular sodium levels in single living cells. Since the fluorescence of sodium-sensitive dyes in cells is significantly different from that in an aqueous solution, the fluorescence signal is calibrated in situ indirectly using ionophores for equalizing external and intracellular ion concentration. Attempts to compare data obtained using fluorescent probes and by direct flame emission analysis are sparse and results are inaccurate. Methods We determined the intracellular sodium concentration in U937 cells by flow cytometry using the Na+-sensitive probe Asante Natrium Green-2 (ANG), and by standard flame emission photometry combined with the cellular water determination by cell density in Percoll gradient. The intracellular Na+ concentrations was modified using known ionophores or, alternatively, by blocking the sodium pump with ouabain or by causing cell apoptosis with staurosporine. Results It is revealed that both methods are comparable when intracellular sodium concentration was modified by ouabain-mediated blockage of the sodium pump or staurosporine-induced apoptosis. The ANG fluorescence of cells treated with ionophores is approximately two times lower than that in cells with the same Na+ concentration but not treated with ionophores. Although the mechanism is still unknown, this effect should be taken into account when a quantitative assessment of the concentration of intracellular sodium is required. Conclusion The sodium sensitive dye ANG-2 is a sensitive and useful probe for determination changes in Na+ content and concentration both in single cells and subcellular microparticles. The ANG fluorescence determined in the studied cells in the absence of ionophores, cannot be used as a measure of the real intracellular concentration of Na+ if calibration was carried out in the presence of ionophores.

Assessing the expression of channels on the cell membrane is a necessary step in studying the functioning of ion channels in living cells. We explore, first, if endogenous VRAC can be assayed using flow cytometry and a commercially available antibody against an extracellular loop of the LRRC8A, also known as SWELL1, subunit of the VRAC channel. The second goal is to determine if an increase in the number of VRAC channels at the cell membrane is responsible for an increase in chloride permeability of the membrane in two well-known cases: during staurosporine (STS)-induced apoptosis and after water balance disturbance caused by hypotonic medium. Human suspension lymphoid cells U937 were used as they are suitable for flow fluorometry and because we have recently studied their membrane chloride permeability during apoptosis. We found that surface expression of endogenous LRRC8A subunits can be quantified in living U937 cells using flow fluorometry with the Alomone Lab antibody. Further, we revealed that treatment of cells for 1 hour using STS or a hypotonic solution did not change the number of LRRC8A subunits to the extent that would correspond to changes in the membrane chloride permeability determined by ion content analysis. This indicates that prolonged increase in chloride permeability of the cell membrane during apoptotic cell shrinkage or cell volume regulation under hypotonicity in U937 cells occurs without altering cell surface expression of VRAC.

New complex compounds LnL3·nH2O (n = 5–10) have been synthesized on the basis of Eu3+, Gd3+, and Tb3+ salts and quinoline-4-carboxylic acid derivatives obtained via the Pfitzinger reaction. Composition and structure of the ligands and the resulting complex compounds have been confirmed by NMR and IR spectroscopy, thermogravimetry, and complexometric titration. Europium complex with 1,2,3,4-tetrahydroacridine-9-carboxylic acid has exhibited efficient luminescence.

2,4-Dioxo-3-azaspiro[5.5]undecane-1,5-dicarbonitrile reacted with primary amines and formaldehyde on heating in boiling ethanol to give mixtures of 7-alkyl-2,4-dioxo-3,7-diazaspiro[bicyclo[3.3.1]nonane- 9,1′-cyclohexane]-1,5-dicarbonitriles and their ammonium salts. The former were isolated in 26–71% after acidification of the reaction mixture.

Traumatic brain injury (TBI) often causes massive brain cell death accompanied by the accumulation of toxic factors in interstitial and cerebrospinal fluids. The persistence of the damaged brain area is not transient and may occur within days and weeks. Chaperone Hsp70 is known for its cytoprotective and antiapoptotic activity, and thus, a therapeutic approach based on chemically induced Hsp70 expression may become a promising approach to lower post-traumatic complications. To simulate the processes of secondary damage, we used an animal model of TBI and a cell model based on the cultivation of target cells in the presence of cerebrospinal fluid (CSF) from injured rats. Here we present a novel low molecular weight substance, PQ-29, which induces the synthesis of Hsp70 and empowers the resistance of rat C6 glioma cells to the cytotoxic effect of rat cerebrospinal fluid taken from rats subjected to TBI. In an animal model of TBI, PQ-29 elevated the Hsp70 level in brain cells and significantly slowed the process of the apoptosis in acceptor cells in response to cerebrospinal fluid action. The compound was also shown to rescue the motor function of traumatized rats, thus proving its potential application in rehabilitation therapy after TBI. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. Ministry of Education and Science of the Russian Federation, Minobrnauka: 0124-2019-002 Russian Foundation for Basic Research, RFBR: 20-33-70102 Russian Science Foundation, RSF: 18-74-10087 Funding: This research was funded by Russian Science Foundation, research project #18-74-10087 (V.F.L., E.A.D., M.A.M., E.R.M.), Russian Foundation for Basic Research, research project #20-33-70102 (I.A.U., O.N.C., V.N.C, M.?.T., I.V.G.), and by The Ministry of Education and Science of Russian Federation № 0124-2019-002 (R.V.S., N.D.A., B.A.M.).

Monovalent ions, sodium in particular, are involved in fundamental cell functions, such as water balance and electric processes, intra- and intercellular signaling, cell movement, pH regulation and metabolite transport into and out of cells. Fluorescent probes are indispensable tools for monitoring intracellular sodium levels in single living cells in heterogeneous cell populations and tissues. Since the fluorescence of sodium-sensitive dyes in cells is significantly different from that in an aqueous solution, the fluorescence signal is calibrated in situ by changing the concentration of extracellular sodium in the presence of ionophores, making the membrane permeable to sodium and equilibrating its intra- and extracellular concentrations. The reliability of this calibration method has not been well studied. Here, we compare the determinations of the intracellular sodium concentration by flame emission photometry and flow cytometry using the Na+-sensitive probe Asante Natrium Green-2 (ANG). The intracellular Na+ concentration was altered using known ionophores or, alternatively, by blocking the sodium pump with ouabain or by causing cell apoptosis with staurosporine. The use of U937 cells cultured in suspension allowed the fluorometry of single cells by flow cytometry and flame emission analysis of samples checked for uniform cell populations. It is revealed that the ANG fluorescence of cells treated with ionophores is approximately two times lower than that in cells with the same Na+ concentration but not treated with ionophores. Although the mechanism is still unknown, this effect should be taken into account when a quantitative assessment of the concentration of intracellular sodium is required. Sodium sensitive fluorescent dyes are widely used at present, and the problem is practically significant.

Method for production of alpha emitter 149Tb by irradiation of 151Eu with 70 MeV 3He nuclei is proposed. For the first time, the cross sections for the formation of isotopes 149,150,151,152Tb were measured experimentally using a stack foil technique in the 3He particles energy range 70 → 12 MeV. The thick target yield of 149Tb is 39 MBq/μAh, or 230 MBq/μA 149Tb at saturation. The optimal energy range from the point of view of radioisotopic purity is 70 → 40 MeV. At these conditions about 150 MBq/μA 149Tb can be produced in 8 hours irradiation, which is sufficient for therapeutic applications. The main impurities are 150Tb (~100% in activity) and 151Tb (~30% in activity). The proposed method surpasses its counterparts by the high content of the target isotope in the natural mixture and the simplicity of the radiochemical separation of 149Tb from the bulk target material.

Immunosuppressive activity of a tumor is provided by constituents of its microenvironment (TME), immune cells, particularly macrophages, which, instead of protecting the organism, render cancer cells more aggressive and metastatically active. A solid tumor is a spacious structure; a naive macrophage, on its way through the tumor, encounters newer cell populations; and its functioning can be improved. In our study, we employed the method of sequential cocultivation of monocyte-like THP-1 cells with A431 human epidermoid cancer cells and explored the changes in the behavior of both cell counterparts depending on cocultivation stage, cytokine profiles, and metalloproteinase 2 and 9 (MMP) activity. We found that the first contact of the monocyte with tumor cells already increased the tumor cell proliferation and migration, release of protumorigenic cytokines, and monocyte polarization into M2 phenotype. One of the most abundant cytokines induced by the cocultivation was tumor necrosis factor, TNF-alpha, a potent inducer of apoptosis. Its release led to the massive death of THP-1 cells, so that at the other stages of cocultivation, a weakened population of macrophages could not affect the behavior of tumor cells. In conclusion, the macrophage function in TME strongly depends on its cytokine content and the data reported here elucidate one scenario of interaction between stromal and cancer cells in a real tumor.

Cancer cells are known to contain high levels of the heat shock protein 70 kDa (Hsp70), which mediates increased cell proliferation, escape from programmed cell death, enhanced invasion, and metastasis. A part of Hsp70 molecules may release from cancer cells and affect the behavior of adjacent stromal cells. To explore the effects of Hsp70 on the status of monocytes/macrophages in the tumor locale, we incubated human carcinoma cells of three distinct lines with normal and reduced content of Hsp70 with THP1 monocytes. Using two methods, we showed that the cells with knock-down of Hsp70 released a lower amount of protein in the extracellular medium. Three cycles of the co-cultivation of cancer and monocytic cells led to the secretion of several cytokines typical of the tumor microenvironment (TME) and to pro-cancer activation of the monocytes/macrophages as established by elevation of F4/80 and arginase-1 markers. Unexpectedly, the efficacy of epithelial&ndash, mesenchymal transition and resistance of carcinoma cells to anticancer drugs after incubation with monocytic cells were more pronounced in cells with lower Hsp70, e.g., releasing less Hsp70 into the extracellular milieu. These data suggest that Hsp70 released from tumor cells into the TME is able, together with the development of an anti-cancer immune response, to limit the conversion of a considerable part of monocytic cells to the pro-tumor phenotype.

Many evidence shows that K+ ions are required for cell proliferation, however, changes in intracellular K+ concentration during transition of cells from quiescence to cycling are insufficiently studied. Here, we show using flame emission assay that a long-term increase in cell K+ content per g cell protein is a mandatory factor for transition of quiescent human peripheral blood lymphocytes (PBL) to proliferation induced by phytohemagglutinin, phorbol ester with ionomycin, and anti-CD3 antibodies with interleukin-2 (IL-2). The long-term increase in K+ content is associated with IL-2-dependent stage of PBL activation and accompanies the growth of small lymphocytes and their transformation into blasts. Inhibition of PBL proliferation with drugs specific for different steps of G0/G1/S transit prevented both blast-transformation and an increase in K+ content per cell protein. Determination of the water content in cells by measuring the density of cells in the Percoll gradient showed that, unlike the K+ content, the concentration of K+ in cell water remains unchanged, since water and K+ change in parallel. Correlation of proliferation with high cell K+ and water content has been confirmed by the data obtained in comparative study of PBL and permanently cycling Jurkat cells. Our data suggest that K+ is important for successful proliferation as the main intracellular ion that participates in regulation of cell water content during cell transition from quiescence to proliferation. We concluded that high K+ content in cells and the associated high water content is a characteristic feature of proliferating cells.

Combinational anticancer therapy demonstrates increased efficiency, as it targets different cell-survival mechanisms and allows the decrease of drug dosages that are often toxic to normal cells. Inhibitors of the heat shock response (HSR) are known to reduce the efficiency of proteostasis mechanisms in many cancerous cells, and therefore, may be employed as anti-tumor drug complements. However, the application of HSR inhibitors is limited by their cytotoxicity, and we suggested that milder inhibitors may be employed to sensitize cancer cells to a certain drug. We used a heat-shock element-luciferase reporter system and discovered a compound, CL-43, that inhibited the levels of heat shock proteins 40, 70 (Hsp70), and 90 kDa in HCT-116 cells and was not toxic for cells of several lines, including normal human fibroblasts. Consequently, CL-43 was found to reduce colony formation and motility of HCT-116 in the appropriate assays suggesting its possible application in the exploration of biology of metastasizing tumors. Importantly, CL-43 elevated the growth-inhibitory and cytotoxic activity of etoposide, cisplatin, and doxorubicin suggesting that the pro-drug has broad prospect for application in a variety of anti-tumor therapy schedules.

CdSe and CdTe-based semiconductor fluorescent nanocrystals, also called quantum dots (QDs), attract the attention of biologists due to their wide range of emission in a visible light interval, high fluorescence quantum yield and photostability. However, their application is limited because of possible toxicity of cadmium. Indeed, there is a probability of metal leakage from QDs cores as a result of damage of both inorganic and organic layers of shells covering QDs. An alternative to cadmium QDs could be nanostructures having as a core, for example, non-toxical indium phosphide (InP), also emitting in the visible region of the spectrum. At present, there is few works on the use of these particles in biology. In this study, a comparative analysis of the spectral-luminescent properties of two InP/ZnS-QDs samples coated with PEG carrying- COOH or -NH2 functional groups was performed. The obtained data were compared with the characteristics of CdSe/ZnS-QDs coated with PEG. The photophysical properties of all QDs in aqueous solution corresponded to the information claimed by manufacturers, but the fluorescence quantum yield of InP-based nanoparticles was found to be lower than that of CdSe-QDs. We also show that the photoluminescence of all types of QDs at pH 4.0 was lower than at pH 7.4, while the decrease in fluorescence intensity was minimal in the case of QDs-PEG-COOH. Studying the uptake of all three types of QDs by J774 macrophages, we found that the fluorescence spectra of internalized QDs do not change in comparison with those in solution. All three types of QDs after 24 hours of incubation were accumulated in the cells, but while QDs-NH2 and QDs without reactive groups were detected mainly in vesicular-like discrete structures, the QDs-COOH were diffusely distributed throughout the cytoplasm. This fact indicates different mechanisms of interaction with cell membranes. In nonphagocytic HeLa cells all types of QDs behaved similarly, but the overall level of cells fluorescence was much lower. This may be due to both reduced nonspecific uptake and possible quenching of QDs fluorescence in acidic endolysosomes. Cytofluorimetric analysis of propidium iodide accumulation showed that after 24 hours incubation with all studied types of QDs as well as in control (no QDs), the proportion of dead HeLa cells did not exceed 10%. Thus, it has been demonstrated that non-toxic InP-based QDs can be used as an effective tool for biological research.

A decrease in flow cytometric forward light scatter (FSC) is commonly interpreted as a sign of apoptotic cell volume decrease (AVD). However, the intensity of light scattering depends not only on the cell size but also on its other characteristics, such as hydration, which may affect the scattering in the opposite way. That makes estimation of AVD by FSC problematic. Here, we aimed to clarify the relationship between light scattering, cell hydration (assayed by buoyant density) and cell size by the Coulter technique. We used human lymphoid cells U937 exposed to staurosporine, etoposide or hypertonic stress as an apoptotic model. An initial increase in FSC was found to occur in apoptotic cells treated with staurosporine and hypertonic solutions; it is accompanied by cell dehydration and is absent in apoptosis caused by etoposide that is consistent with the lack of dehydration in this case. Thus, the effect of dehydration on the scattering signal outweighs the effect of reduction in cell size. The subsequent FSC decrease, which occurred in parallel to accumulation of annexin-positive cells, was similar in apoptosis caused by all three types of inducers. We conclude that an increase, but not a decrease in light scattering, indicates the initial cell volume decrease associated with apoptotic cell dehydration.

The reaction of tetra(phenylethynyl)tin with aromatic aldehydes in the presence of ZnCl2 afforded α-acetylene ketones in a yield of 77–98%.

Fluorescent probes are a popular and indispensable tool for monitoring sodium concentration in living cells in situ. Calibration of fluorescent probes inside cells commonly uses ionophores to equilibrate intracellular and external ion concentrations. Here we test this calibration method using in parallel classical flame emission assay. Suspension human lymphoma cells allow both flow cytometry fluorometric study and flame emission assay. The most sensitive Na+ fluorescent probe ANG-2 and the most common ionophores were tested. Cellular Na+ was altered for calibration in three different ways: by stopping the sodium pump with ouabain, by inducing of apoptosis with staurosporine, and by gramicidin or amphotericin B treatment. We found that ANG-2 fluorescence in cells treated with gramicidin or amphotericin was about two fold lower than in the cells with the same sodium concentration but without ionophores. The equal fluorescence measured in the absence and in the presence of ionophores corresponds to different cell sodium concentrations. No effect of gramicidin on hydrolyzed ANG was observed in vitro. The mechanism, by which gramicidin decreases ANG fluorescence in cells is unlikely to be physical quenching and remains obscure. We conclude that ANG fluorescence does not display realistic cell Na+ if fluorescence in cell is measured in ionophore absence while calibrated in its presence.

Stress-induced premature senescence program is known to be activated in cells by various genotoxic stressors, and oxidative stress is considered to be the main of those. To this end, many studies discover antioxidants as protective anti-aging agents. In the current study, we examined the effects of different antioxidants (Tempol, resveratrol, NAC, DPI) on the mesenchymal stem cells maintained in normal physiological conditions. We used high, but non-cytotoxic antioxidant doses which are widely used in laboratory practice to protect cells from oxidative damage. We show that these substances induce reversible block of cell proliferation and do not cause any genotoxic effects when applied to the quiescent cells. However, the same doses of the same substances, when applied to the proliferating cells, can induce irreversible cell cycle arrest, DNA strand breaks accumulation and DNA damage response activation. As a consequence, antioxidant-induced DNA damage results in the stress-induced premature senescence program activation. We conclude that high doses of antioxidants, when applied to the proliferating cells that maintain physiological levels of reactive oxygen species, can cause DNA damage and induce premature senescence which suggests to re-estimate believed unconditional anti-aging antioxidant properties.

O,O-Dialkyl S-(1,1-dimethyl-2-oxoethyl) dithiophosphates, 2-(dialkoxythiophosphorylthio)-substituted aldehydes with branched carbon groups, were obtained by hydrolysis of phosphoryl-containing iminium salts. The reaction with primary amines results in imines containing acetal group in different positions. Tri- and tetra-substituted perhydro-1,3-diazoles and oxazoles containing a phosphorus atom in the side chain were prepared by reacting the aldehydes with O,Nand N,N-dinucleophiles.